1
<title>Sliced VBI Data Interface</title>
3
<para>VBI stands for Vertical Blanking Interval, a gap in the
4
sequence of lines of an analog video signal. During VBI no picture
5
information is transmitted, allowing some time while the electron beam
6
of a cathode ray tube TV returns to the top of the screen.</para>
8
<para>Sliced VBI devices use hardware to demodulate data transmitted
9
in the VBI. V4L2 drivers shall <emphasis>not</emphasis> do this by
10
software, see also the <link linkend="raw-vbi">raw VBI
11
interface</link>. The data is passed as short packets of fixed size,
12
covering one scan line each. The number of packets per video frame is
15
<para>Sliced VBI capture and output devices are accessed through the
16
same character special files as raw VBI devices. When a driver
17
supports both interfaces, the default function of a
18
<filename>/dev/vbi</filename> device is <emphasis>raw</emphasis> VBI
19
capturing or output, and the sliced VBI function is only available
20
after calling the &VIDIOC-S-FMT; ioctl as defined below. Likewise a
21
<filename>/dev/video</filename> device may support the sliced VBI API,
22
however the default function here is video capturing or output.
23
Different file descriptors must be used to pass raw and sliced VBI
24
data simultaneously, if this is supported by the driver.</para>
27
<title>Querying Capabilities</title>
29
<para>Devices supporting the sliced VBI capturing or output API
30
set the <constant>V4L2_CAP_SLICED_VBI_CAPTURE</constant> or
31
<constant>V4L2_CAP_SLICED_VBI_OUTPUT</constant> flag respectively, in
32
the <structfield>capabilities</structfield> field of &v4l2-capability;
33
returned by the &VIDIOC-QUERYCAP; ioctl. At least one of the
34
read/write, streaming or asynchronous <link linkend="io">I/O
35
methods</link> must be supported. Sliced VBI devices may have a tuner
40
<title>Supplemental Functions</title>
42
<para>Sliced VBI devices shall support <link linkend="video">video
43
input or output</link> and <link linkend="tuner">tuner or
44
modulator</link> ioctls if they have these capabilities, and they may
45
support <link linkend="control">control</link> ioctls. The <link
46
linkend="standard">video standard</link> ioctls provide information
47
vital to program a sliced VBI device, therefore must be
51
<section id="sliced-vbi-format-negotitation">
52
<title>Sliced VBI Format Negotiation</title>
54
<para>To find out which data services are supported by the
55
hardware applications can call the &VIDIOC-G-SLICED-VBI-CAP; ioctl.
56
All drivers implementing the sliced VBI interface must support this
57
ioctl. The results may differ from those of the &VIDIOC-S-FMT; ioctl
58
when the number of VBI lines the hardware can capture or output per
59
frame, or the number of services it can identify on a given line are
60
limited. For example on PAL line 16 the hardware may be able to look
61
for a VPS or Teletext signal, but not both at the same time.</para>
63
<para>To determine the currently selected services applications
64
set the <structfield>type </structfield> field of &v4l2-format; to
65
<constant> V4L2_BUF_TYPE_SLICED_VBI_CAPTURE</constant> or <constant>
66
V4L2_BUF_TYPE_SLICED_VBI_OUTPUT</constant>, and the &VIDIOC-G-FMT;
67
ioctl fills the <structfield>fmt.sliced</structfield> member, a
68
&v4l2-sliced-vbi-format;.</para>
70
<para>Applications can request different parameters by
71
initializing or modifying the <structfield>fmt.sliced</structfield>
72
member and calling the &VIDIOC-S-FMT; ioctl with a pointer to the
73
<structname>v4l2_format</structname> structure.</para>
75
<para>The sliced VBI API is more complicated than the raw VBI API
76
because the hardware must be told which VBI service to expect on each
77
scan line. Not all services may be supported by the hardware on all
78
lines (this is especially true for VBI output where Teletext is often
79
unsupported and other services can only be inserted in one specific
80
line). In many cases, however, it is sufficient to just set the
81
<structfield>service_set</structfield> field to the required services
82
and let the driver fill the <structfield>service_lines</structfield>
83
array according to hardware capabilities. Only if more precise control
84
is needed should the programmer set the
85
<structfield>service_lines</structfield> array explicitly.</para>
87
<para>The &VIDIOC-S-FMT; ioctl modifies the parameters
88
according to hardware capabilities. When the driver allocates
89
resources at this point, it may return an &EBUSY; if the required
90
resources are temporarily unavailable. Other resource allocation
91
points which may return <errorcode>EBUSY</errorcode> can be the
92
&VIDIOC-STREAMON; ioctl and the first &func-read;, &func-write; and
93
&func-select; call.</para>
95
<table frame="none" pgwide="1" id="v4l2-sliced-vbi-format">
97
<structname>v4l2_sliced_vbi_format</structname></title>
99
<colspec colname="c1" colwidth="3*" />
100
<colspec colname="c2" colwidth="3*" />
101
<colspec colname="c3" colwidth="2*" />
102
<colspec colname="c4" colwidth="2*" />
103
<colspec colname="c5" colwidth="2*" />
104
<spanspec namest="c3" nameend="c5" spanname="hspan" />
108
<entry><structfield>service_set</structfield></entry>
109
<entry spanname="hspan"><para>If
110
<structfield>service_set</structfield> is non-zero when passed with
111
&VIDIOC-S-FMT; or &VIDIOC-TRY-FMT;, the
112
<structfield>service_lines</structfield> array will be filled by the
113
driver according to the services specified in this field. For example,
114
if <structfield>service_set</structfield> is initialized with
115
<constant>V4L2_SLICED_TELETEXT_B | V4L2_SLICED_WSS_625</constant>, a
116
driver for the cx25840 video decoder sets lines 7-22 of both
117
fields<footnote><para>According to <link
118
linkend="ets300706">ETS 300 706</link> lines 6-22 of the
119
first field and lines 5-22 of the second field may carry Teletext
120
data.</para></footnote> to <constant>V4L2_SLICED_TELETEXT_B</constant>
121
and line 23 of the first field to
122
<constant>V4L2_SLICED_WSS_625</constant>. If
123
<structfield>service_set</structfield> is set to zero, then the values
124
of <structfield>service_lines</structfield> will be used instead.
125
</para><para>On return the driver sets this field to the union of all
126
elements of the returned <structfield>service_lines</structfield>
127
array. It may contain less services than requested, perhaps just one,
128
if the hardware cannot handle more services simultaneously. It may be
129
empty (zero) if none of the requested services are supported by the
130
hardware.</para></entry>
134
<entry><structfield>service_lines</structfield>[2][24]</entry>
135
<entry spanname="hspan"><para>Applications initialize this
136
array with sets of data services the driver shall look for or insert
137
on the respective scan line. Subject to hardware capabilities drivers
138
return the requested set, a subset, which may be just a single
139
service, or an empty set. When the hardware cannot handle multiple
140
services on the same line the driver shall choose one. No assumptions
141
can be made on which service the driver chooses.</para><para>Data
142
services are defined in <xref linkend="vbi-services2" />. Array indices
143
map to ITU-R line numbers (see also <xref linkend="vbi-525" /> and <xref
144
linkend="vbi-625" />) as follows: <!-- No nested
145
tables, sigh. --></para></entry>
150
<entry>Element</entry>
151
<entry>525 line systems</entry>
152
<entry>625 line systems</entry>
157
<entry><structfield>service_lines</structfield>[0][1]</entry>
158
<entry align="center">1</entry>
159
<entry align="center">1</entry>
164
<entry><structfield>service_lines</structfield>[0][23]</entry>
165
<entry align="center">23</entry>
166
<entry align="center">23</entry>
171
<entry><structfield>service_lines</structfield>[1][1]</entry>
172
<entry align="center">264</entry>
173
<entry align="center">314</entry>
178
<entry><structfield>service_lines</structfield>[1][23]</entry>
179
<entry align="center">286</entry>
180
<entry align="center">336</entry>
182
<!-- End of line numbers table. -->
186
<entry spanname="hspan">Drivers must set
187
<structfield>service_lines</structfield>[0][0] and
188
<structfield>service_lines</structfield>[1][0] to zero.</entry>
192
<entry><structfield>io_size</structfield></entry>
193
<entry spanname="hspan">Maximum number of bytes passed by
194
one &func-read; or &func-write; call, and the buffer size in bytes for
195
the &VIDIOC-QBUF; and &VIDIOC-DQBUF; ioctl. Drivers set this field to
196
the size of &v4l2-sliced-vbi-data; times the number of non-zero
197
elements in the returned <structfield>service_lines</structfield>
198
array (that is the number of lines potentially carrying data).</entry>
202
<entry><structfield>reserved</structfield>[2]</entry>
203
<entry spanname="hspan">This array is reserved for future
204
extensions. Applications and drivers must set it to zero.</entry>
210
<!-- See also vidioc-g-sliced-vbi-cap.sgml -->
211
<table frame="none" pgwide="1" id="vbi-services2">
212
<title>Sliced VBI services</title>
214
<colspec colname="c1" colwidth="2*" />
215
<colspec colname="c2" colwidth="1*" />
216
<colspec colname="c3" colwidth="1*" />
217
<colspec colname="c4" colwidth="2*" />
218
<colspec colname="c5" colwidth="2*" />
219
<spanspec namest="c3" nameend="c5" spanname="rlp" />
222
<entry>Symbol</entry>
224
<entry>Reference</entry>
225
<entry>Lines, usually</entry>
226
<entry>Payload</entry>
231
<entry><constant>V4L2_SLICED_TELETEXT_B</constant>
232
(Teletext System B)</entry>
233
<entry>0x0001</entry>
234
<entry><xref linkend="ets300706" />, <xref linkend="itu653" /></entry>
235
<entry>PAL/SECAM line 7-22, 320-335 (second field 7-22)</entry>
236
<entry>Last 42 of the 45 byte Teletext packet, that is
237
without clock run-in and framing code, lsb first transmitted.</entry>
240
<entry><constant>V4L2_SLICED_VPS</constant></entry>
241
<entry>0x0400</entry>
242
<entry><xref linkend="ets300231" /></entry>
243
<entry>PAL line 16</entry>
244
<entry>Byte number 3 to 15 according to Figure 9 of
245
ETS 300 231, lsb first transmitted.</entry>
248
<entry><constant>V4L2_SLICED_CAPTION_525</constant></entry>
249
<entry>0x1000</entry>
250
<entry><xref linkend="eia608" /></entry>
251
<entry>NTSC line 21, 284 (second field 21)</entry>
252
<entry>Two bytes in transmission order, including parity
253
bit, lsb first transmitted.</entry>
256
<entry><constant>V4L2_SLICED_WSS_625</constant></entry>
257
<entry>0x4000</entry>
258
<entry><xref linkend="itu1119" />, <xref linkend="en300294" /></entry>
259
<entry>PAL/SECAM line 23</entry>
263
Bit 7 6 5 4 3 2 1 0 x x 13 12 11 10 9
267
<entry><constant>V4L2_SLICED_VBI_525</constant></entry>
268
<entry>0x1000</entry>
269
<entry spanname="rlp">Set of services applicable to 525
270
line systems.</entry>
273
<entry><constant>V4L2_SLICED_VBI_625</constant></entry>
274
<entry>0x4401</entry>
275
<entry spanname="rlp">Set of services applicable to 625
276
line systems.</entry>
282
<para>Drivers may return an &EINVAL; when applications attempt to
283
read or write data without prior format negotiation, after switching
284
the video standard (which may invalidate the negotiated VBI
285
parameters) and after switching the video input (which may change the
286
video standard as a side effect). The &VIDIOC-S-FMT; ioctl may return
287
an &EBUSY; when applications attempt to change the format while i/o is
288
in progress (between a &VIDIOC-STREAMON; and &VIDIOC-STREAMOFF; call,
289
and after the first &func-read; or &func-write; call).</para>
293
<title>Reading and writing sliced VBI data</title>
295
<para>A single &func-read; or &func-write; call must pass all data
296
belonging to one video frame. That is an array of
297
<structname>v4l2_sliced_vbi_data</structname> structures with one or
298
more elements and a total size not exceeding
299
<structfield>io_size</structfield> bytes. Likewise in streaming I/O
300
mode one buffer of <structfield>io_size</structfield> bytes must
301
contain data of one video frame. The <structfield>id</structfield> of
302
unused <structname>v4l2_sliced_vbi_data</structname> elements must be
305
<table frame="none" pgwide="1" id="v4l2-sliced-vbi-data">
307
<structname>v4l2_sliced_vbi_data</structname></title>
313
<entry><structfield>id</structfield></entry>
314
<entry>A flag from <xref linkend="vbi-services" />
315
identifying the type of data in this packet. Only a single bit must be
316
set. When the <structfield>id</structfield> of a captured packet is
317
zero, the packet is empty and the contents of other fields are
318
undefined. Applications shall ignore empty packets. When the
319
<structfield>id</structfield> of a packet for output is zero the
320
contents of the <structfield>data</structfield> field are undefined
321
and the driver must no longer insert data on the requested
322
<structfield>field</structfield> and
323
<structfield>line</structfield>.</entry>
327
<entry><structfield>field</structfield></entry>
328
<entry>The video field number this data has been captured
329
from, or shall be inserted at. <constant>0</constant> for the first
330
field, <constant>1</constant> for the second field.</entry>
334
<entry><structfield>line</structfield></entry>
335
<entry>The field (as opposed to frame) line number this
336
data has been captured from, or shall be inserted at. See <xref
337
linkend="vbi-525" /> and <xref linkend="vbi-625" /> for valid
338
values. Sliced VBI capture devices can set the line number of all
339
packets to <constant>0</constant> if the hardware cannot reliably
340
identify scan lines. The field number must always be valid.</entry>
344
<entry><structfield>reserved</structfield></entry>
345
<entry>This field is reserved for future extensions.
346
Applications and drivers must set it to zero.</entry>
350
<entry><structfield>data</structfield>[48]</entry>
351
<entry>The packet payload. See <xref
352
linkend="vbi-services" /> for the contents and number of
353
bytes passed for each data type. The contents of padding bytes at the
354
end of this array are undefined, drivers and applications shall ignore
361
<para>Packets are always passed in ascending line number order,
362
without duplicate line numbers. The &func-write; function and the
363
&VIDIOC-QBUF; ioctl must return an &EINVAL; when applications violate
364
this rule. They must also return an &EINVAL; when applications pass an
365
incorrect field or line number, or a combination of
366
<structfield>field</structfield>, <structfield>line</structfield> and
367
<structfield>id</structfield> which has not been negotiated with the
368
&VIDIOC-G-FMT; or &VIDIOC-S-FMT; ioctl. When the line numbers are
369
unknown the driver must pass the packets in transmitted order. The
370
driver can insert empty packets with <structfield>id</structfield> set
371
to zero anywhere in the packet array.</para>
373
<para>To assure synchronization and to distinguish from frame
374
dropping, when a captured frame does not carry any of the requested
375
data services drivers must pass one or more empty packets. When an
376
application fails to pass VBI data in time for output, the driver
377
must output the last VPS and WSS packet again, and disable the output
378
of Closed Caption and Teletext data, or output data which is ignored
379
by Closed Caption and Teletext decoders.</para>
381
<para>A sliced VBI device may support <link
382
linkend="rw">read/write</link> and/or streaming (<link
383
linkend="mmap">memory mapping</link> and/or <link linkend="userp">user
384
pointer</link>) I/O. The latter bears the possibility of synchronizing
385
video and VBI data by using buffer timestamps.</para>
390
<title>Sliced VBI Data in MPEG Streams</title>
392
<para>If a device can produce an MPEG output stream, it may be
393
capable of providing <link
394
linkend="sliced-vbi-format-negotitation">negotiated sliced VBI
395
services</link> as data embedded in the MPEG stream. Users or
396
applications control this sliced VBI data insertion with the <link
397
linkend="v4l2-mpeg-stream-vbi-fmt">V4L2_CID_MPEG_STREAM_VBI_FMT</link>
400
<para>If the driver does not provide the <link
401
linkend="v4l2-mpeg-stream-vbi-fmt">V4L2_CID_MPEG_STREAM_VBI_FMT</link>
402
control, or only allows that control to be set to <link
403
linkend="v4l2-mpeg-stream-vbi-fmt"><constant>
404
V4L2_MPEG_STREAM_VBI_FMT_NONE</constant></link>, then the device
405
cannot embed sliced VBI data in the MPEG stream.</para>
407
<para>The <link linkend="v4l2-mpeg-stream-vbi-fmt">
408
V4L2_CID_MPEG_STREAM_VBI_FMT</link> control does not implicitly set
409
the device driver to capture nor cease capturing sliced VBI data. The
410
control only indicates to embed sliced VBI data in the MPEG stream, if
411
an application has negotiated sliced VBI service be captured.</para>
413
<para>It may also be the case that a device can embed sliced VBI
414
data in only certain types of MPEG streams: for example in an MPEG-2
415
PS but not an MPEG-2 TS. In this situation, if sliced VBI data
416
insertion is requested, the sliced VBI data will be embedded in MPEG
417
stream types when supported, and silently omitted from MPEG stream
418
types where sliced VBI data insertion is not supported by the device.
421
<para>The following subsections specify the format of the
422
embedded sliced VBI data.</para>
425
<title>MPEG Stream Embedded, Sliced VBI Data Format: NONE</title>
426
<para>The <link linkend="v4l2-mpeg-stream-vbi-fmt"><constant>
427
V4L2_MPEG_STREAM_VBI_FMT_NONE</constant></link> embedded sliced VBI
428
format shall be interpreted by drivers as a control to cease
429
embedding sliced VBI data in MPEG streams. Neither the device nor
430
driver shall insert "empty" embedded sliced VBI data packets in the
431
MPEG stream when this format is set. No MPEG stream data structures
432
are specified for this format.</para>
436
<title>MPEG Stream Embedded, Sliced VBI Data Format: IVTV</title>
437
<para>The <link linkend="v4l2-mpeg-stream-vbi-fmt"><constant>
438
V4L2_MPEG_STREAM_VBI_FMT_IVTV</constant></link> embedded sliced VBI
439
format, when supported, indicates to the driver to embed up to 36
440
lines of sliced VBI data per frame in an MPEG-2 <emphasis>Private
441
Stream 1 PES</emphasis> packet encapsulated in an MPEG-2 <emphasis>
442
Program Pack</emphasis> in the MPEG stream.</para>
444
<para><emphasis>Historical context</emphasis>: This format
445
specification originates from a custom, embedded, sliced VBI data
446
format used by the <filename>ivtv</filename> driver. This format
447
has already been informally specified in the kernel sources in the
448
file <filename>Documentation/video4linux/cx2341x/README.vbi</filename>
449
. The maximum size of the payload and other aspects of this format
450
are driven by the CX23415 MPEG decoder's capabilities and limitations
451
with respect to extracting, decoding, and displaying sliced VBI data
452
embedded within an MPEG stream.</para>
454
<para>This format's use is <emphasis>not</emphasis> exclusive to
455
the <filename>ivtv</filename> driver <emphasis>nor</emphasis>
456
exclusive to CX2341x devices, as the sliced VBI data packet insertion
457
into the MPEG stream is implemented in driver software. At least the
458
<filename>cx18</filename> driver provides sliced VBI data insertion
459
into an MPEG-2 PS in this format as well.</para>
461
<para>The following definitions specify the payload of the
462
MPEG-2 <emphasis>Private Stream 1 PES</emphasis> packets that contain
463
sliced VBI data when <link linkend="v4l2-mpeg-stream-vbi-fmt">
464
<constant>V4L2_MPEG_STREAM_VBI_FMT_IVTV</constant></link> is set.
465
(The MPEG-2 <emphasis>Private Stream 1 PES</emphasis> packet header
466
and encapsulating MPEG-2 <emphasis>Program Pack</emphasis> header are
467
not detailed here. Please refer to the MPEG-2 specifications for
468
details on those packet headers.)</para>
470
<para>The payload of the MPEG-2 <emphasis>Private Stream 1 PES
471
</emphasis> packets that contain sliced VBI data is specified by
472
&v4l2-mpeg-vbi-fmt-ivtv;. The payload is variable
473
length, depending on the actual number of lines of sliced VBI data
474
present in a video frame. The payload may be padded at the end with
475
unspecified fill bytes to align the end of the payload to a 4-byte
476
boundary. The payload shall never exceed 1552 bytes (2 fields with
477
18 lines/field with 43 bytes of data/line and a 4 byte magic number).
480
<table frame="none" pgwide="1" id="v4l2-mpeg-vbi-fmt-ivtv">
481
<title>struct <structname>v4l2_mpeg_vbi_fmt_ivtv</structname>
488
<entry><structfield>magic</structfield>[4]</entry>
490
<entry>A "magic" constant from <xref
491
linkend="v4l2-mpeg-vbi-fmt-ivtv-magic" /> that indicates
492
this is a valid sliced VBI data payload and also indicates which
493
member of the anonymous union, <structfield>itv0</structfield> or
494
<structfield>ITV0</structfield>, to use for the payload data.</entry>
498
<entry>(anonymous)</entry>
502
<entry>struct <link linkend="v4l2-mpeg-vbi-itv0">
503
<structname>v4l2_mpeg_vbi_itv0</structname></link>
505
<entry><structfield>itv0</structfield></entry>
506
<entry>The primary form of the sliced VBI data payload
507
that contains anywhere from 1 to 35 lines of sliced VBI data.
508
Line masks are provided in this form of the payload indicating
509
which VBI lines are provided.</entry>
513
<entry>struct <link linkend="v4l2-mpeg-vbi-itv0-1">
514
<structname>v4l2_mpeg_vbi_ITV0</structname></link>
516
<entry><structfield>ITV0</structfield></entry>
517
<entry>An alternate form of the sliced VBI data payload
518
used when 36 lines of sliced VBI data are present. No line masks are
519
provided in this form of the payload; all valid line mask bits are
520
implcitly set.</entry>
526
<table frame="none" pgwide="1" id="v4l2-mpeg-vbi-fmt-ivtv-magic">
527
<title>Magic Constants for &v4l2-mpeg-vbi-fmt-ivtv;
528
<structfield>magic</structfield> field</title>
533
<entry align="left">Defined Symbol</entry>
534
<entry align="left">Value</entry>
535
<entry align="left">Description</entry>
540
<entry><constant>V4L2_MPEG_VBI_IVTV_MAGIC0</constant>
542
<entry>"itv0"</entry>
543
<entry>Indicates the <structfield>itv0</structfield>
544
member of the union in &v4l2-mpeg-vbi-fmt-ivtv; is valid.</entry>
547
<entry><constant>V4L2_MPEG_VBI_IVTV_MAGIC1</constant>
549
<entry>"ITV0"</entry>
550
<entry>Indicates the <structfield>ITV0</structfield>
551
member of the union in &v4l2-mpeg-vbi-fmt-ivtv; is valid and
552
that 36 lines of sliced VBI data are present.</entry>
558
<table frame="none" pgwide="1" id="v4l2-mpeg-vbi-itv0">
559
<title>struct <structname>v4l2_mpeg_vbi_itv0</structname>
565
<entry>__le32</entry>
566
<entry><structfield>linemask</structfield>[2]</entry>
567
<entry><para>Bitmasks indicating the VBI service lines
568
present. These <structfield>linemask</structfield> values are stored
569
in little endian byte order in the MPEG stream. Some reference
570
<structfield>linemask</structfield> bit positions with their
571
corresponding VBI line number and video field are given below.
572
b<subscript>0</subscript> indicates the least significant bit of a
573
<structfield>linemask</structfield> value:<screen>
574
<structfield>linemask</structfield>[0] b<subscript>0</subscript>: line 6 first field
575
<structfield>linemask</structfield>[0] b<subscript>17</subscript>: line 23 first field
576
<structfield>linemask</structfield>[0] b<subscript>18</subscript>: line 6 second field
577
<structfield>linemask</structfield>[0] b<subscript>31</subscript>: line 19 second field
578
<structfield>linemask</structfield>[1] b<subscript>0</subscript>: line 20 second field
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<structfield>linemask</structfield>[1] b<subscript>3</subscript>: line 23 second field
580
<structfield>linemask</structfield>[1] b<subscript>4</subscript>-b<subscript>31</subscript>: unused and set to 0</screen></para></entry>
583
<entry>struct <link linkend="v4l2-mpeg-vbi-itv0-line">
584
<structname>v4l2_mpeg_vbi_itv0_line</structname></link>
586
<entry><structfield>line</structfield>[35]</entry>
587
<entry>This is a variable length array that holds from 1
588
to 35 lines of sliced VBI data. The sliced VBI data lines present
589
correspond to the bits set in the <structfield>linemask</structfield>
590
array, starting from b<subscript>0</subscript> of <structfield>
591
linemask</structfield>[0] up through b<subscript>31</subscript> of
592
<structfield>linemask</structfield>[0], and from b<subscript>0
593
</subscript> of <structfield>linemask</structfield>[1] up through b
594
<subscript>3</subscript> of <structfield>linemask</structfield>[1].
595
<structfield>line</structfield>[0] corresponds to the first bit
596
found set in the <structfield>linemask</structfield> array,
597
<structfield>line</structfield>[1] corresponds to the second bit
598
found set in the <structfield>linemask</structfield> array, etc.
599
If no <structfield>linemask</structfield> array bits are set, then
600
<structfield>line</structfield>[0] may contain one line of
601
unspecified data that should be ignored by applications.</entry>
607
<table frame="none" pgwide="1" id="v4l2-mpeg-vbi-itv0-1">
608
<title>struct <structname>v4l2_mpeg_vbi_ITV0</structname>
614
<entry>struct <link linkend="v4l2-mpeg-vbi-itv0-line">
615
<structname>v4l2_mpeg_vbi_itv0_line</structname></link>
617
<entry><structfield>line</structfield>[36]</entry>
618
<entry>A fixed length array of 36 lines of sliced VBI
619
data. <structfield>line</structfield>[0] through <structfield>line
620
</structfield>[17] correspond to lines 6 through 23 of the
621
first field. <structfield>line</structfield>[18] through
622
<structfield>line</structfield>[35] corresponds to lines 6
623
through 23 of the second field.</entry>
629
<table frame="none" pgwide="1" id="v4l2-mpeg-vbi-itv0-line">
630
<title>struct <structname>v4l2_mpeg_vbi_itv0_line</structname>
637
<entry><structfield>id</structfield></entry>
638
<entry>A line identifier value from
639
<xref linkend="ITV0-Line-Identifier-Constants" /> that indicates
640
the type of sliced VBI data stored on this line.</entry>
644
<entry><structfield>data</structfield>[42]</entry>
645
<entry>The sliced VBI data for the line.</entry>
651
<table frame="none" pgwide="1" id="ITV0-Line-Identifier-Constants">
652
<title>Line Identifiers for struct <link
653
linkend="v4l2-mpeg-vbi-itv0-line"><structname>
654
v4l2_mpeg_vbi_itv0_line</structname></link> <structfield>id
655
</structfield> field</title>
660
<entry align="left">Defined Symbol</entry>
661
<entry align="left">Value</entry>
662
<entry align="left">Description</entry>
667
<entry><constant>V4L2_MPEG_VBI_IVTV_TELETEXT_B</constant>
670
<entry>Refer to <link linkend="vbi-services2">
671
Sliced VBI services</link> for a description of the line payload.</entry>
674
<entry><constant>V4L2_MPEG_VBI_IVTV_CAPTION_525</constant>
677
<entry>Refer to <link linkend="vbi-services2">
678
Sliced VBI services</link> for a description of the line payload.</entry>
681
<entry><constant>V4L2_MPEG_VBI_IVTV_WSS_625</constant>
684
<entry>Refer to <link linkend="vbi-services2">
685
Sliced VBI services</link> for a description of the line payload.</entry>
688
<entry><constant>V4L2_MPEG_VBI_IVTV_VPS</constant>
691
<entry>Refer to <link linkend="vbi-services2">
692
Sliced VBI services</link> for a description of the line payload.</entry>
705
sgml-parent-document: "v4l2.sgml"
706
indent-tabs-mode: nil